Enhancement and suppression of the Peyer's patch immune response by systemic priming

Mice were immunized by a single injection of sheep red blood cells (SRBC) in Freund's complete adjuvant (FCA), and their Peyer's patch (PP) immune response was studied by in vitro culture, or transfer of PP cells into irradiated recipients. After both intra-peritoneal (i.p.) or sub-cutaneous (s.c.) immunization, PP cells showed greatly enhanced in vitro IgM plaque forming cell (PFC) responses to SRBC. The in vitro enhanced response was antigen-specific and was apparent up to 11 weeks post-immunization. It was also shown that PP from primed mice contained nylon wool non-adherent cells (N/A) which could enhance normal PP PFC responses in vitro. Peyer's patch cells from i.p. immunized mice transferred into irradiated recipients generated greatly enhanced splenic IgG and IgA anti-SRBC responses when compared to the response generated by normal PP cells. In contrast, PP cells taken from mice immunized s.c. showed suppressed IgG and IgA responses in irradiated recipients. Furthermore, whereas N/A cells from the PP of i.p. immunized mice greatly enhanced the response of normal PP cells in the irradiated recipients, N/A cells from the PP of s.c. immunized mice noticeably suppressed this response. These data show that systemic immunization can markedly alter PP immune function, and that these effects are probably T cell mediated.